A hydro scheme on the River Lyon has been visited by SEPA officers, following reports of silt escaping into the water which could threaten aquatic wildlife. Local residents at Invervar were alarmed by discolouration of the Highland Perthshire river which is home to endangered freshwater pearl mussels. Previously silt pollution from another hydro scheme in 2010 wiped out mussels and led to steep penalties for the developer and contractors.

SEPA is investigating reports of silt pollution in the River Lyon where a hydro scheme is currently under construction.

Residents from Invervar in Glenlyon, contacted SEPA officers after spotting a large ribbon of silt in the river, one of only 71 watercourses in Scotland known to still to support the mussels.

Local residents have told the PA that SEPA officers visited on Friday and conducted interviews to establish the facts.

They were asked about a recent “major” silting incident which saw an area half the river’s width discoloured with earth debris.

The PA understands a prosecution is being pursued.

Yesterday a SEPA spokesperson said: “A member of our local team has confirmed that we are currently investigating reports of silt pollution. However, as these investigations are ongoing it would be inappropriate to provide any further information at this moment.”

In 2013 successful prosecutions were made in the wake of a nearby hydro scheme at Inverinain releasing silt which devastated the mussels in the surrounding water. The creatures, which feed using water filters, starved to death under a thick covering of silt.

The incident was considered serious because Scotland may now hold approximately half the known remaining breeding populations in the world.

Shawater Ltd, who designed the project, pleaded guilty to permitting the pollution of the River Lyon to occur, and at Perth Sheriff Court on February 18, 2013 was fined £4000.

The specialist wildlife fiscal told the court that it remained unclear how long it would take for the mussel population in the River Lyon to recover, if at all.

Soon after, two contractors, Alan Smith and Charles Kippen, admitted to causing damage to the river. They were fined a total of £11,000.

The hydro scheme at Invervar is part of the Glen Lyon Partnership hydro project – a series of seven hydro developments linked to Aberfeldy-based Green Highland Renewables (GHR).

GHR founder, landowner Alistair Riddell, stepped down as managing director in November 2011.